Letermovir (oral/injection)

Letermovir is an antiviral medicine that helps prevent cytomegalovirus (CMV) infection after a stem cell (bone marrow) transplant from a donor in adults and children who are at least 6 months old and weigh at least 88 pounds (40 kg).

Letermovir is also used to prevent CMV in adults and children who are at least 6 months old and weigh at least 88 pounds (40 kg) after receiving a kidney transplant, especially if they are at higher risk of developing a CMV infection.

Your doctor will do tests to ensure that letermovir is the right treatment for you.

Letermovir may also be used for other purposes not mentioned in this medication guide.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Letermovir oral is taken by mouth once per day with or without food.

Letermovir injection is injected into a vein by a healthcare provider only if you are unable to take medicine by mouth.

Letermovir oral granules are mixed with one to three teaspoons of soft foods such as applesauce, yogurt, or pudding, and the mixed medicine should be taken within 10 minutes. Letermovir oral granules can also be given through a feeding tube. Talk to your doctor or pharmacist if you do not understand these instructions.

Doses are based on weight. Your dose may change if you gain or lose weight.

Your condition may get worse if you stop using letermovir suddenly. Ask your doctor before stopping the medicine.

Do not crush or chew letermovir oral pellets. Swallow the tablet whole and do not crush, break, or dissolve it.

Store letermovir in the original container at room temperature away from moisture and heat.

Tell your doctor about all your current medicines. Many drugs can affect letermovir, and some drugs should not be used together.

Some drugs should not be taken with letermovir. Your treatment plan may be adjusted if you also take:

• pimozide;
• cholesterol medication--pitavastatin, simvastatin; or
• ergot medicine--dihydroergotamine, ergotamine, ergonovine, methylergonovine.

Let your doctor know if you have ever had:

• diabetes;
• high cholesterol or triglycerides (a type of fat in the blood); or
• liver or kidney disease.

Inform your doctor if you are pregnant or breastfeeding.

Get emergency medical help if you have signs of an allergic reaction: hives, trouble breathing, swelling of your face, lips, tongue, or throat.

Letermovir may cause serious side effects. Call your doctor immediately if you experience:

• fast or irregular heartbeats.

Common side effects of letermovir may include:

• nausea, diarrhea, vomiting, stomach pain;
• swelling in your arms or legs;
• cough;
• headache; or
• feeling tired.

This is not a complete list of side effects and others may happen. Call your doctor for medical advice about side effects. You can report side effects to the FDA at 1-800-FDA-1088.

Usual Adult Dose for CMV Prophylaxis:

480 mg orally or IV once a dayComments:-The IV formulation should be administered at a constant rate over 1 hour.-Hematopoietic Stem Cell Transplant (HSCT): This drug should be started between Day 0 and Day 28 post-HSCT (before or after engraftment) and should continue through Day 100 post-HSCT.---In patients at risk for late CMV infection and disease, this drug may be continued through Day 200 post-HSCT.-Kidney Transplant: This drug should be started between Day 0 and Day 7 and should continue through Day 200 posttransplant.Uses:-For the prophylaxis of CMV infection and disease in CMV-seropositive recipients (R+) of an allogeneic HSCT-For the prophylaxis of CMV disease in kidney transplant recipients at high risk (donor CMV seropositive/recipient CMV seronegative [D+/R-])

Use the medicine as soon as possible, but skip the missed dose if it is almost time for your next dose. Do not take two doses at the same time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Follow your doctor's instructions regarding any limits on food, drinks, or activities.

Sometimes it is not safe to use certain medicines together. Some drugs can change the amount of other drugs in your blood, which might increase side effects or reduce how well the medicines work.

If you are also using cyclosporine, your letermovir dose will need to be changed.

Other drugs may affect letermovir, including prescription and over-the-counter medicines, vitamins, and herbal products. Inform your doctor about all other medicines you take.